5.1x Windows Guest Video Playback 2x speed - No Sound

Description

Problem:
With 5.1x if I play back a video in Windows 7 guest then it does not have sound and the video plays back at about 2x speed. This is true in several media players. Also, true in Firefox 47, 48 and Google Chrome 52. So this issue is systemic. Tried disabling 2D and 3D with the same issue. Went through several installs, cold power downs, reboots and many experiments.

Thank you for the information. I did do a complete uninstall and install of 5.1.6 and there are still sound issues. I believe that it has to do with the new qt5 and alsa+ICH AC97 used in my guests. I notice that if I play two or more videos then the sound is disabled. It was not playing back at 2x. Anyway, I reverted back to 5.0.26. When I get more time I will try again and send you the detailed logs as requested.